function s1_generate_a_series_of_files(){
	for index in $(seq 1 100);do
		echo -n "$index" > "/tmp/new_file$index"
	done
}
function s2_list_4_files_in_long_format_about_account_and_group(){
	ls -l /etc/{passwd,group,shadow,gshadow} | sort
}
function s3_find_items_related_to_given_username(){
	grep -h "$1" /etc/passwd /etc/shadow | sort
}
function s4_find_items_related_to_given_group_name(){
	grep -h "$1" /etc/group /etc/gshadow | sort
}
function s5_create_groups_for_given_group_names(){
	groupadd rnd
	groupadd itoperation
}
function s6_create_users_and_set_their_group_as_required(){
	useradd adam
	useradd bob
	useradd calvin
	useradd david
	useradd edward
	usermod -aG rnd adam
	usermod -aG rnd bob
	usermod -aG rnd edward
	usermod -aG itoperation calvin
	usermod -aG itoperation david
}
function s7_change_users_shell(){
	usermod -s /usr/bin/sh adam
	usermod -s /usr/bin/sh edward
}
function s8_set_password_change_policy(){
	for user in adam bob calvin david edward; do
		chage -m 10 -M 60 -W 10 $user
	done
}
function s9_set_password_for_five_users(){
	usernames=(adam bob calvin david edward)
	passwords=("$1" "$2" "$3" "$4" "$5")
	for i in {0..4}; do
		echo "${usernames[$i]}:${passwords[$i]}" | sudo chpasswd
	done
}
function s10_lock_bobs_password(){
	usermod -p '!' bob
}
function s11_include_adam_into_wheel_group(){
	usermod -aG wheel adam
}
function s12_change_files_permission(){
	for num in $(seq 3 3 99); do
		chmod 640 /tmp/new_file$num
	done
}

